Messages in this thread Patch in this message |  | | Date | Fri, 07 Feb 2003 09:48:34 -0600 | From | Corey Minyard <> | Subject | Re: [PATCH] 2.4.20 drivers/cdrom/cdu31a.c |
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I don't guess anyone I've sent documentation to has taken up support of this drive. It's amazing that any of these things are still running, since I think they stop manufacturing them in 1994. I don't think I have a machine that it will even work in any more. I guess they were well-built drives.
The change you are suggesting is probably not the best, you probably need to fix it higher up to do multiple requests if nsect is > 4. I've attached a patch. It compiles, but I obviously can't test it.
Looking through the code, there's obvious SMP problems and a few other things. I have a new machine with an ISA slot (I think), I might try to plug it in.
-Corey
Mauricio Martinez wrote:
>This patch fixes the kernel oops while trying to read a data CD. Thanks to >Brian Gerst and Faik Uygur for your suggestions. > >It looks like the variable nblocks must be <= 4 so the read ahead buffer >size is not exceeded (which is the cause of the oops). Changing its value >doesn't seem to be the right way, but it makes the device work properly. > >Feedback of any sort welcome. > > > --- drivers/cdrom/cdu31a.c.old Fri Feb 7 09:16:08 2003 +++ drivers/cdrom/cdu31a.c Fri Feb 7 09:42:53 2003 @@ -1341,7 +1341,7 @@ #endif } -/* read data from the drive. Note the nsect must be <= 4. */ +/* read data from the drive. Note the nblocks must be <= 4. */ static void read_data_block(char *buffer, unsigned int block, @@ -1364,7 +1364,7 @@ bytesleft = nblocks * 512; offset = 0; - /* If the data in the read-ahead does not match the block offset, + /* If the data in the read ahead does not match the block offset, then fix things up. */ if (((block % 4) * 512) != ((2048 - readahead_dataleft) % 2048)) { sony_next_block += block % 4; @@ -1384,9 +1384,9 @@ readahead_buffer + (2048 - readahead_dataleft), readahead_dataleft); - readahead_dataleft = 0; bytesleft -= readahead_dataleft; offset += readahead_dataleft; + readahead_dataleft = 0; } else { /* The readahead will fill the whole buffer, get the data and return. */ @@ -1533,7 +1533,7 @@ /* * The OS calls this to perform a read or write operation to the drive. - * Write obviously fail. Reads to a read ahead of sony_buffer_size + * Writes obviously fail. Reads to a read ahead of sony_buffer_size * bytes to help speed operations. This especially helps since the OS * uses 1024 byte blocks and the drive uses 2048 byte blocks. Since most * data access on a CD is done sequentially, this saves a lot of operations. @@ -1546,6 +1546,7 @@ unsigned int res_size; int num_retries; unsigned long flags; + char *buffer; #if DEBUG @@ -1616,6 +1617,7 @@ block = CURRENT->sector; nblock = CURRENT->nr_sectors; + buffer = CURRENT->buffer; if (!sony_toc_read) { printk("CDU31A: TOC not read\n"); @@ -1695,8 +1697,17 @@ } } - read_data_block(CURRENT->buffer, block, nblock, - res_reg, &res_size); + if (nblock >= 4) { + read_data_block(buffer, block, 4, + res_reg, &res_size); + nblock -= 4; + block += 4; + buffer += 4 * 512; + } else { + read_data_block(buffer, block, nblock, + res_reg, &res_size); + nblock = 0; + } if (res_reg[0] == 0x20) { if (num_retries > MAX_CDU31A_RETRIES) { end_request(0); @@ -1714,6 +1725,8 @@ translate_error(res_reg[1]), block, nblock); } + goto try_read_again; + } else if (nblock > 0) { goto try_read_again; } else { end_request(1); |  |